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What is electric current?

An electric current is a flow of charged particles, such as electrons or ions, moving through an electrical conductor or space. It is defined as the net rate of flow of electric charge through a surface.

How do we generate electric currents?

We know charge is the property of a particle due to which it can interact with electric fields and experience electric forces.

We use this property of charge to have electric currents; we connect a conductor with a potential difference (battery) so there an electric field sets up in the conductor causing the free-charged particles (electrons) to drift opposite to the direction of the electric field. Hence we get an electric current.


But electrons have another property too i.e mass, which is the property of a particle by which it can experience Gravitational forces.

I need help in designing a setup to produce electric current using the property of gravitational mass of electrons.

So if we have a long conductor wire and a Gravitational field is switched on such that it's direction is along the length of the wire then electrons (which are free) will experience a Gravitational force and we should have a flow of charges, the electric current.

But there can be some problems in this:

  1. The gravitational forces are way more weaker than the electric forces.
  2. As free electrons move away from one end of the wire, they leave this end positive, so a mean electric attractive force acts on the free electrons tending to prevent their further movement.

Possible solutions and crux

  1. Electrons in a conductor are loosely bound to the nucleus and at any temperature they will have enough thermal energy so that they can be free and do continuous random motion like gas molecules in a container which is also called brownian motion. And our sir has told us that brownian motion ceases at absolute zero temperature.
  2. If we connect the wire from top to the earth then the charge vacancy can be fulfilled by charge flow from the earth.

So above thought experiment suggests generating current using gravity instead of electric potential difference.

Some study materials

I don't thought that I will need to do it but now I felt the need to do this after an answer asking for "how one would switch on a gravitational field" and there can be more like that comments in future maybe. So here is a Wikipedia page about thought experiment

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    $\begingroup$ Electrons in a conductor are bound to atoms (albeit looser than in nonconductors) by electrical forces. Your experiment won't work simply because the electric force is many ($\approx 10^{39}$) orders of magnitude greater than the gravitational force. $\endgroup$
    – joseph h
    Commented Jul 13, 2023 at 7:05
  • $\begingroup$ See also Does a rotating disk develop a potential difference between the centre and rim? That question asks about a centripetal force rather than a gravitational force but the principle is the same. $\endgroup$ Commented Jul 13, 2023 at 8:18
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    $\begingroup$ We use gravity to make water flow through turbines in hydroelectric dams, but that's only useful because the Earth's weather systems, powered by the Sun, keep returning water to the reservoir in the form of rain. Even if your scheme would work (but see @josephh 's comment, above) where is the reservoir for the electrons, and what what process would return the electrons to the top of it to maintain the current flow? $\endgroup$ Commented Jul 13, 2023 at 10:26
  • $\begingroup$ In the attached question on Gravitational Hall effect the answer by @JohnRennie is not clear to me properly at some places like it says that electron gains potential energy on moving from top to bottom which is opposite to what I believe but still I have an intuition that the answer also points about the snag which the answer on this post claims and I think it should be resolved by the point no. 2 in the solutions part of this question. $\endgroup$
    – D13G
    Commented Jul 14, 2023 at 19:43
  • $\begingroup$ And the second answer by @anna is too much technical for me to comprehend so if someone can simplify it a little bit will be helpful. $\endgroup$
    – D13G
    Commented Jul 14, 2023 at 19:44

1 Answer 1

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I don't know how one would switch on a gravitational field, though whirling the wire about one end would be equivalent to applying a non-uniform gravitational field.

The snag is that as free electrons move away from one end of the wire, they leave this end positive, so a mean electric attractive force acts on the free electrons tending to prevent their further movement.

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